1. Field of the Invention
The present invention relates to a resin-seal type semiconductor device containing an insulating circuit substrate on which a semiconductor element is mounted.
2. Description of the Related Art
FIG. 9 is a cross-sectional view showing a conventional SIP (Single-In-Line-Package) type resin-sealed semiconductor device.
A semiconductor element 2 is fixed on a metal lead frame 1 by means of solder 3. The semiconductor element is electrically connected to a first end portion of an outer lead 5 by a metal wire 4. The metal lead frame 1, semiconductor element 2 and the first end portion of the outer lead 5 are sealed with a resin 6 by a transfer molding process. A second end portion of the outer lead projects from the resin 6.
FIG. 10 is a cross-sectional view showing a conventional DIP (Dual-In-Line-Package) type resin-sealed semiconductor device. The parts common to those shown in FIG. 9 are denoted by like reference numerals, and only different parts will be described.
Second end portions of outer leads 5, which are opposite to the first end portions thereof sealed with resin 6, are projected in two directions.
The SIP- and DIP-type resin-sealed semiconductor devices can be manufactured at low material cost in simple assembly steps, and these devices are suitable for mass-production.
In the above semiconductor devices, a radiation part situated under the metal lead frame 1 is also sealed with resin. Thus, compared to a semiconductor device having a radiation part formed of a ceramic material, the saturation heat resistance Rth (.degree.C/W) of the above devices is higher. Consequently, in the conventional resin-seal type semiconductor devices, the power loss Pc(W) allowable to the resin or a casing is low.
In addition, in the case where two or more semiconductor elements are mounted in the conventional resin-seal type semiconductor device, it is very difficult to form wiring patterns connecting the semiconductor elements, since the lead frame cannot be made finer or thinner. Thus, two or more semiconductor elements cannot be mounted in the conventional resin-seal type semiconductor device. Consequently, the density of mounted semiconductor elements is not satisfactorily high in this semiconductor device.